Herndon, of Ohio, served several deployments in Iraq and Afghanistan, the Record-Courier reported. During a tour in Afghanistan in 2010, three people he was with were killed when they were targeted by an IED.

Marines Mark Juarez and Matthew Ballard, and Rupert Hamer, a British journalist, died. He said he ran the Boston Marathon on Sunday for them.

“I run in honor of them. They are not here anymore. I am here, and I am able," Herndon told the news outlet. "I am lucky to still have all my limbs. I can still be active. I find fuel in the simple idea that I can run. Some cannot."

He said that despite his small plights — whether his feet hurt or he's tired from running — he reminds himself why he continues, in true "Semper Fi" fashion.

"I just keep saying their names out loud to myself. They went through much worse, so I run for them and their families.”

In a Facebook post, Herndon shared a photo of a pair of orange Nike sneakers, but with a sentimental detail: three small golden plates featuring the names of Juarez, Ballard and Hamer are weaved in with the shoelaces. The plates served as a reminder to Herndon of why he keeps running.

Videos posted online Monday show Herndon kept his word. Close to the end, he crawled to the finish line, finishing the race 11,334 overall.

Nicole Darrah covers breaking and trending news for FoxNews.com. You can follow her on Twitter at @nicoledarrah.

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